One type of printing device well known in the art prints color images using a color material, such as ink or toner, in a plurality of colors, such as cyan, magenta, yellow, and black.
This type of printing device converts image data representing an image to be printed (image data in the RGB color spacer for example) to a color system corresponding to the colors of the color material used in printing (the CMYK color space, for example) and prints the image based on the converted image data. Since colors in an image are rendered by superimposing each color material, satisfactory printing results may not be obtained for some colors when the total amount of color material used to render the color is excessive.
Therefore, techniques have been proposed for printing images by converting image data so as to restrict the total amount of color material used in the printing operation. For example, a multifunction device described in Japanese patent application publication No. 2003-125225 prints an image based on image data in the RGB color space inputted from an input unit by first converting this image data to image data in the CMYK color space corresponding to the colors of the color material. Subsequently, further the multifunction device converts the image data so that the total amount of color material is less than a predetermined limit.